Finding fruits of the sea in Acadia Park

On our annual summer vacation in Maine, we spend most of our time in and around Acadia National Park, a destination for our family since we were kids. It’s an incredibly beautiful area, and either from hikes on the high trails or walks along the rocky coast, the views are varied and spectacular.

Last week, on a roadway right along the shore, I found shrub roses growing wild. The dense plants were particularly eye-catching at this time of year, with plenty of blossoms still emerging while the round, plump seedpods — the “hips” — were turning from green to orange.

Automatically, I assumed that these were native roses. (In my mind, in a fit of wishful thinking, the designation “national park” somehow conferred exotic plant-free status, but that’s of course not the case.) The pretty-yet-tough rose was Rugosa Rose (Rosa rugosa), a species native to eastern Asia (China, Japan, Korea and southeast Siberia). Unlike the flat leaves of other roses, the leaves of Rosa rugosa are distinctively corrugated.

A little digging reminded me that this species is highly tolerant of salt spray, making it a perfect fit for coastal areas. Much tougher than other roses and needing little in the way of maintenance, it is widely used in landscaping. One of its chief applications is in planting along roadways, since it can tolerate the salt that is put down during snow and ice storms.

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I also learned that Rosa rugosa hybridizes readily with many other roses, and is valued by rose breeders for its considerable resistance to the diseases rose rust and rose black spot. There are many hybrid varieties that gardeners can choose from. The hips are high in Vitamin C and can be used to make preserves and herbal tea.

The one downside of the rugosa rose is that suckers freely from its roots, eventually growing to form dense thickets if left to grow unchecked. These thickets easily out-compete native species. A book published earlier this year, titled Schoodic Point: History on the Edge of Acadia National Park, describes some of the studies of the vegetation of the area. In it, author Allen K. Workman states, “One common pattern of change for plants in the park area and beyond has been the gradual crowding out of more native species by those more recently introduced. Plants that were labeled ‘uncommon’ there in the 1890s are very often now rare or extinct, while some formerly unknown species have become invasive.”Rosa rugosa is not the fastest of invaders, but it does get around. It was initially introduced to the United States as a garden and landscape ornamental around 1845 and was first reported as escaped from cultivation on Nantucket Island, Massachusetts, in 1899. Ten years later it was recorded throughout the island. Part of the plant’s success in spreading is that the hips float and observation shows that the seeds can remain viable for close to a year. Thus, the ocean ends up being a perfect transport system, spreading the plants further along the coast..Seeing these shrubs reminded me of beach plums and the jam that my mother-in-law used to make. My in-laws lived on Cape Cod, where — for those folks savvy and energetic enough — there were plenty of the small purple fruits to harvest in late summer/early fall and process into jam.

The rugosa rose is sometimes called “beach plum,” but the true beach plum is a different species. Beach plum is Prunus maritima, a species of plum native to the East Coast of the United States, from Maine south to Maryland. “Prunus,” puts it in the same genus of trees and shrubs that includes plums, cherries, peaches, nectarines, apricots and almonds. The prunus genus, like rosa, is included in the larger botanical family, Rosaceae, so the two plants are related, just higher up the family tree.